Process for the production of water and solvent-free hydrogenated nitrile rubbers

A process for producing hydrogenated nitrile rubber containing less than 1.25 wt % volatile compounds, the process comprising removing volatile compounds from a fluid (F) having a viscosity of at maximum 200,000 Pa*s (measured at 100° C. and at a shear rate of 1/s) and containing:

• (i) at least one hydrogenated nitrile rubber comprising repeating units derived from at least one conjugated diene, at least one α,β-unsaturated nitrile, and optionally one or more copolymerizable monomer, and
• (ii) at least one volatile compound,
• and the process comprises the steps of:
• a) treating the fluid (F) in at least one concentrator unit comprising at least a heater (2), a degassing vessel (4) and a vapor line, whereby the fluid (F) is heated to produce a heated fluid (G), and the heated fluid (G) is fed into, and degassed in a degassing vessel where part of the volatile compounds are removed via the vapor line to obtain a concentrated fluid (H),
• b) reheating the concentrated fluid (H) from step a) in at least one reheating unit to obtain a reheated concentrated fluid (L) having a viscosity in the range of 10,000 mPa*s to 300,000 mPa*s;
• c) feeding the reheated concentrated fluid (L) from step b) into at least one extruder unit comprising at least an extruder degassing section comprising at least a conveying section, a vent port with one or more vapor lines, at least one accumulating section, and an outlet section;
• d) introducing at least one stripping agent into the reheated concentrated fluid (L) the extruder unit;
• and
• e) removing an additional portion of the volatile compounds from the reheated concentrated fluid (L) through the vent ports and vapor lines as the reheated concentrated fluid (L) passes through the extruder unit to produce, at the outlet section, hydrogenated nitrile rubber containing less than 1.25 wt % volatile compounds based on the mass of the hydrogenated nitrile rubber.